US8950555B2ActiveUtilityPatentIndex 73
Method for scheduling cars in elevator systems to minimize round-trip times
Est. expiryApr 21, 2031(~4.8 yrs left)· nominal 20-yr term from priority
Inventors:BRAND MATTHEW
B66B 2201/213B66B 1/2458B66B 2201/222B66B 2201/215
73
PatentIndex Score
4
Cited by
14
References
18
Claims
Abstract
A set of cars in an elevator system are scheduled by assigning passengers to the cars such that a current schedule for each car does not exceed a predetermined maximum number of stops per round trip, and the car is filled as near as possible to a maximum capacity at a predetermined bottleneck.
Claims
exact text as granted — not AI-modifiedI claim:
1. A method for scheduling a set of cars in an elevator system, the method comprising for each car the steps of:
assigning passengers to the car such that a current schedule (CS) for the car does not exceed a predetermined maximum number of stops per round trip (MS); and
filling the car as near as possible to a maximum capacity (MC) at a predetermined bottleneck.
2. The method of claim 1 , further comprising:
assigning the passengers with common stops to the same car to minimize round-trip times.
3. The method of claim 2 , further comprising:
approximating the round-trip times by an affine function of the number of stops and the number of the passengers.
4. The method of claim 1 , further comprising:
estimating an optimal number of stops by simulating car assignments with a hard limit on the number of stops.
5. The method of claim 1 , further comprising:
estimating an optimal number of stops by deriving of a quadratic function from physical system parameters and an expected arrival rate.
6. The method of claim 1 , further comprising:
estimating an optimal number of stops by estimating the number of stops needed to service all passengers when an expected arrival rate of the passengers matches a bottleneck capacity.
7. The method of claim 1 , wherein an expected number E[X] of stops for all cars is
E
[
X
]
=
f
d
(
1
-
(
(
f
-
d
)
c
n
)
(
fc
n
)
)
≈
f
d
(
1
-
(
1
-
n
cf
)
d
c
)
,
where f are possible destination floors, d is a number of cars with f/d stop locations, c is a per-floor capacity, and n represents passenger requests drawn from a uniform distribution.
8. The method of claim 7 , further comprising:
dividing the expected number of stops by the number of cars to determine the expected number of stops per car.
9. The method of claim 1 , wherein a total number of requested stops is less than or equal to the MS, and a cumulative waiting time for all the passengers making all the stops is determined by a deterministic discrete event simulation.
10. The method of claim 1 , further comprising:
scheduling any passengers to be picked up and can be accommodated within the CS as long as the MS for the car is not exceeded.
11. The method of claim 10 , wherein the scheduling is in an order of boarding by the passengers.
12. The method of claim 1 , wherein a schedule with an optimal number of stops is estimated by simulating car assignments with a hard limit on the number of stops, and selecting the hard limit giving an optimal average cumulative waiting time.
13. The method of claim 1 , wherein a schedule with an optimal number of stops is estimated by deriving of a quadratic function from physical system parameters and an expected arrival rate of the passengers.
14. The method of claim 1 , wherein a schedule with an optimal number of stops is estimated by estimating the number of stops needed to service all passengers when an expected arrival rate of the passengers matches a bottleneck capacity.
15. The method of claim 1 , further comprising:
constructing a list of all unscheduled arrival floors and destination floors of remaining uncommitted passengers.
16. The method of claim 13 , further comprising:
adding greedily stops that maximize a number of passengers on board the car.
17. The method of claim 13 , further comprising:
adding stops that minimally extend a round trip time of the car.
18. The method of claim 15 , further comprising:
adding stops in a chronological order of when the stops are requested.Cited by (0)
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